Above are some links to better show what I mean. I use Pte Jack's method by using gimp to fix the texture file for some miscs that often show up as black when they shouldn't be. It works for most yet on some it leaves a sort of "jagged" unsightly outline like on the weight room warmer here.

Is there any way to fix this through gimp or photoshop? If so, what would need to be edited?

Yeah, that usually happens to me when I fix paintable item's textures too, such as on the Soldier's Viking helmet (visible on the blue helmet in this screenshot: http://i.imgur.com/33m66iL.jpg ). Something to do with how the layer mask isn't antialiased the same way the base colour map is or some such nonsense. I made a few experiments with this and so far I was never able to fully remove the aliasing...

The blue helmet doesn't really seem to show it, at least not from what I see. It's easily hidden since the paint is already supposed to look chipped.

What I've noticed is that when I have to "Choose by color" in gimp it chooses all of the black/white. If you look closely you'll see that the stripes are lined with a tiny line of different shades of gray, you think that could be the issue? If so it's probably no harder than to select it somehow and just change it to match the white/black inside of the stripe. Only question is what kind of messing around would you have to do with the layering and such.